Refrigerating apparatus



Aug. 6, 1935.

C. W. SPOHR REFRIGERATING APPARATUS Filed March 27, 1953 Q? Aug. 6, 1935. c. w. SPOHR 2,010,279

REFRIGERATING APPARATUS Filed March 27, 1935 s Sheets-Sheet 2 Aug. 6, 1935. c. w. SPOHR REFRIGERATING APPARATUS 6' Sheets-Sheet 3 5 /Z A,

Irma/afar Q11 14. 5,0054

Filed March 27, 1933 Aug. 6, 1935. 'c. w. SPOHR REFRIGERATING APPARATUS I 1122 Qrl $520k:

6 Sheets-Sheet 4 Filed March 27, 1933 Aug. 6, 1935. w SPQHR 2,010,279

REFRIGERATING APPARATUS Filed March 27, 1933 6 Sheets-Sheet 5 Fey: 7

44/ ll l/ w m4 2 I am W-fipakr Aug. 6, 1935. c, w SPQHR 2,010,279

REFRIGERATING APPARATUS Filed March 2'7, 1933 6 Sheets-Sheet 6 9 07 N Patented Aug. -6, 1935 PATENT OFFICE REFBIGERATIN G APPARATUS Carl W. Spohr, Chicago, Ill., assignor to Mechanical Refrigerated Car Company, Chicago, 111., a

corporation of Illinois Application March 27, 1933, Serial No. 384 16 Claims. (Cl. 62-426) This invention relates to improvements in refrigerating apparatus and more particularly, but not exclusively, refrigerating apparatus especially arranged and adapted for vehicles such as refrigerator cars, trucks and the like having a revenue-producing or pay-load compartment requiring automatic temperature control within predetermined limits under a wide range of operating conditions. More specifically, the invention relates to that type of refrigerating apparatus employing a flooded recirculating system.

In recirculating systems, the refrigerant is conducted in a circuit broadly comparable to a U-tube, one leg of which is comparatively shielded from the influx of heat and the other is fully exposed to the influx of heat. When the condensed or liquefied refrigerant is in the U-tube, the evaporation or expansion takes place mostly in the exposed or riser leg of the U and hence, 7 due to the greater expansion and formation of vapor bubbles therein, the level rises above the level of the liquefied refrigerant in the shielded or drop leg of the U. Advantage is taken of this difference in levels to draw off the vapors from the exposed or riser leg at a point above the level in the shielded or drop leg and then return or drop the remaining unvaporized liquefled refrigerant back into the shielded or drop leg for recirculation. Among the advantages of such a flooded recirculating system are: simplicity of control; suction vapors of proper character; high heat transfer co-efliciency; relatively small evaporating or expander coil surfaces; high suction pressure and generally increased compressor capacity and improved thermal efficiency.

Under some conditions, however, the flooded recirculating type of refrigerating systems, as heretofore used, possesses serious disadvantages, particularly in the case of refrigerator cars where the usual compressor is operated from the car axle necessarily at widely varying speeds and at times, being completely idle when the car is stationary. Under the conditions necessarily incident to refrigerator car and other vehicle operation, cold accumulators or hold over cold storing arrangements must be provided for satisfactory operation that the same may be drawn upon to cool or maintain the payload compartment when the car and compressor are not running. With the heretofore known types of flooded recirculating systems, the level of the liquefied refrigerant in the pipes or coils must be kept at a comparatively high level for the apparatus to properly function. Hence, when such a system is used in conjunction with a cold accumulator from which the liquefied refrigerant must be able to feed by gravity to the main cooling coils for the pay-load compartment, the cold accumulators must be located relatively high up in the car, resulting in a too top heavy and undesirable high 5 center of gravity arrangement.

Other disadvantages of the heretofore known flooded recirculating refrigerating systems have been found. Such systems are ordinarily designed for a certain definite, most advantageous level 10 of the liquefied refrigerant with an assumed more or less constant rate of evaporation. The more rapid the assumed average rate of evaporation, the lower the desirable liquid level and vice versa. Consequently if, for any reason, the feed of the liquefied refrigerant is throttled so as to lower the level appreciably below the assumed desirable level, danger of superheating of the vapors arises and, vice versa, if the level rises above the assumed desirable level, danger or flooding occurs. Because of the wide range of variationsin the operation of refrigerator cars, particularly with respect to the speed at which the car moves and the outside temperature conditions, it is impracticable with the heretofore known types of flooded recirculating systems, to assume any preferred level of the liquefied refrigerant in the coils because of the danger of resulting disadvantages of superheating and flooding.

One object of this invention is to provide a refrigerating apparatus of the flooded recirculating type so constructed and arranged that it is inherently adapted, under a wide range of conditions, to actively function with only such proportionate part of the evaporating or expander 5 pipes or coils as is necessary to effect the desired cooling under any particular set of conditions prevailing and without danger of excess flooding and with minimized possibility of superheating of the vapors.

Another object of the invention is to provide a flooded recirculating system of refrigeration wherein the refrigerant is circulated in a series of successive stages or steps in such manner that the vapor formed during each stage or step is 5 delivered to the suction line direct and the unvaporized liquefied refrigerant remaining at the end of each stage or step is then passed to the next stage and so on.

Another object of the invention is to provide a refrigerating apparatus of the type indicated, wherein the liquefied refrigerant is passed successively through a series of independent expanders or evaporators, the vapor as successively formed in each expander or evaporator, being a somewhat larger scale.

separated while saturated from the remaining liquefied refrigerant at the exit end of the expander or evaporator, the vapor so successively formed and separated being delivered to the main suction line for return to the compressor or other equivalent means, and the liquefied refrigerant remaining, if any, after the passage through the last of the expanders or evaporators being then returned for recirculation through the first expander or evaporator and so on.

A further object of the invention is to provide a refrigerating apparatus wherein the primary cooling, expander or evaporator coils for tempering the air are combined in such manner with a cold storing or cold accumulating means and a thermostatically governed distributor valve that the maximum refrigerating or cooling effect delivered from the compressor or equivalent is confined to said primary coils when the cooling effect of the latter is required and, when not so required, is delivered to and stored in the cold accumulating means to be thereafter drawn upon when the conditions change.

Still another object of the invention is to provide a refrigerating apparatus of the .flooded recirculating type as specified in each of the preceding stated objects of the invention, which is especially arranged for and adapted for use in maintaining desired temperatures in a refrigerator car or other vehicle.

Other and more specific objects of the invention will more clearly appear from the description and claims hereinafter following.

In the drawings forming a part of this specification, Figure 1 is a simplified and schematic view illustrative of an embodiment of the invention as incorporated in a refrigerator car, the latter being shown in longitudinal vertical section and the compressor employed being indicated as driven from one of the car axles. In this view, the refrigerating apparatus is shown only at one end of the car but, as hereinafter explained, the same apparatus may be employed at the other end of the car except for the omission of certain valves, flash drum and the like, which would be common to the apparatus at both ends. Figure 2 is a vertical, transverse sectional view of a refrigerator car showing the imprevements incorporated therein, Figure 2 corresponding to the section line 2-2 of Figure 3 and certain parts being broken away to clarify the disclosure. Figure 3 is a vertical sectional view taken longitudinally of the refrigerator car and corresponding to the section line 33 of Figure 2, but upon Figure 3a is a continuation of the ceiling coils shown in Figure 3, separated therefrom because of the size limitations of the sheet. Figure 4 is a horizontal sectional view corresponding to the section line l l of Figure 3, parts being broken out to better accommodate the view on the sheet. Figure 5 is a broken vertical sectional view corresponding to the section line 55 of Figure 3. Figure 6 is an enlarged part elevation, part vertical section of the coil arrangement shown in Figure 2 and illustrating in detail more particularly the manner of circulating the refrigerant through the first of the series of expander or evaporating tubes. Figure 7 is an enlarged detailed sectional view illustrating the admission and exit ends of two expander tubes with associated collector or header. Figure 8 is an enlarged vertical sectional view corresponding to the line 8-8 of Figure 4, illustrating more particularly the details of the expansion valve. Figure 9 is a horizontal sec- .at l2, the side walls at l3-I3, and one ofthe bulkheads at It. The bulkhead, as shown in Figures l and 3, is such as to provide an upper opening or passage I5 for incoming warm air and a lower outlet passage I 6 for the cooled air. As customary, the bulkhead may be duplicated at the opposite end of the car, thus dividing the interior of the car into a central payload or revenue-producing compartment l! and end cooling or refrigerating chambers 18. A compressor is indicated conventionally at I9, the same being preferably driven from one of the car axles 20 by pulley 2i, belt 22, intermediate pulley 23 and belt 26 taking over the drive pulley 25 of the compressor. Inasmuch as no specific claim is made to the means for operating the compressor, it is deemed unnecessary to more fully describe the drive, which may be of the same type as that more fully shown and claimed in my prior pending application 620,774, filed July 5, 1932, for improvement in temperature controlled vehicles and to which reference may be had for a full disclosure. From the compressor leads the supply vapor pipe 26, which is preferably run to the roof of the car to a vapor header 2?, which is in communication with condenser coils 28 preferably located on the roof of the car, as shown for instance in the prior Luhr Reissue Patent 17,660, reissued May 13, 1930. The return end of the roof condenser coils conducts the condensed refrigerant to a trap arrangement, designated generally by the reference character A, whence the refrigerant is distributed and passed through the cooling and accumulator coils as hereinafter described, the vapors ultimately being delivered to the suction line 29, which leads back to the compressor, thus completing the circuit. While compressor and condenser coils have been indicated as the preferred means for effecting condensation or liquefaction of the refrigerant, other equivalent means may be utilized, as will be understood by those skilled in the art.

Referring first to the schematic arrangement shown in Figure 1, in order to first obtain a general understanding of the improvements, the liquefied refrigerant is first passed from the trap A through a sealing or expansion valve indicated generally by the reference character B; thence through expansion pipe 30 to a flash drum 31. From the flash drum, the refrigerant is then distributed through a thermostatically controlled distributor valve C to either or both a main cooling coil indicated generally by the reference character D and a cold accumulator coil E disposed within an insulated brine tank 32. The cold accumulator and the main coil D are both preferably located within the bulkhead refrigerating compartment 18. The top ends of the headers of each of the coils D and E (hereinafter described more in detail) are in communication by branch cooling coil D and cold accumulator E are in parallel between the delivery and suction pipes of the compressor, condenser, expander circuit. The arrangement shown in Figure 1 is for one end of the car but, as will be understood, the cooling coil D and cold accumulator E may be duplicated at the opposite end of the car and for this purpose, the branch pipes 36 and 31 are led from the outlet side of the distributor valve 0, preferably beneath the floor of the car to the other end where the same communicate with the inlet ends of the cooling and accumulator coils, respectively. The vapor return from the opposite end of the car is effected through the suction pipe 35 hereinbefore referred to.

Still referring to Figure l, the main cooling coil or expander D comprises, broadly, a plurality of vertically extending headers or collectors 40 and a series of expander orevaporator tubes 505|-52, etc. arranged in a gradually ascending series, each of said expander tubes being of the fiooded recirculating type and further characterized by the fact that, at the outlet end of each of the expander tubes, the vapor formed therein is automatically separated from the unvaporized liquid refrigerant in such manner that the vapor is delivered to a header 40 and the remaining liquid refrigerant then passed on to the next expander tube, thus providing what may be termed a multi-lift or stepped coil. The uppermost or last expander tube 53 of the series, after such vapor as may be formed therein is delivered to the end header 40, then passes the remaining liquefied refrigerant, if any, to an auxiliary ceiling cooling coil arrangement, indicated generally by the reference character F and, more particularly described hereinafter, the coil F being also of the flooded recirculating type but, as shown, not utilizing the multi-lift or step by step feature. Similarly, the coil E of the cold accumulator comprises a series of gradually ascending expander tubes similar to those referred to but not having any auxiliary coil associated therewith.

Fromthe brief description, it will be seen that, depending upon the condition of the distributor valve C, as hereinafter described, all of the refrigerating capacity from the compressor may be delivered solely to the main cooling coils D (and F); or solely to the cold accumulator E; partly to both coils D and E; and also that interchange between the two coils D and E is also available.

Considering next the construction in detail, reference may first be had to Figure 8, illustrating the details of the trap A and expansion valve B. The trap A comprises a shell or chamber preferably located on the underside of the roof of the car and into which the condensed refrigerant is delivered through the pipe 6| at the top thereof. The trap is preferably vented through the pipe 52 to the vapor header 21in order to prevent locking of the refrigerant in the condenser coils 28. The expansion valve B, preferably located on the fioor of the car, comprises a suitable casing 63 having a central chamber in which is disposed a flexible diaphragm 64 di-' viding the chamber into two compartments 65 and 66. The compartment 66 on the lefthand side of the diaphragm as viewed in Figure 8, is in communication through the port 61 with a balance pipe 68 running up into the trap A and having a funnel 59 at the top thereof. The compartment 65 is in communication with the bottom of the trap A through vertical pipe 10. The valve casing is also provided with an additional outlet port 1| in communication with the expansion pipe 30 leading to the flash drum. Between the compartment and port 1| is located an apertured valve nut 12 having a needle opening therein adapted to be controlled by a needle valve 13 carried by the diaphragm 64 and controlling the passage of liquefied refrigerant from the compartment 65 to the expansion pipe 30, as will be obvious. The diaphragm 64 is under the influence of two coil springs 14 and 15 on opposite sides thereof, the tension of the spring 15 being adjusted or regulated by'an adjusting screw 16.

In carrying out the invention, the balance pipe 68 will initially be filled with ice machine oil or equivalent so as to prevent refrigerant from collecting therein and toprovide a substantially constant hydrostatic pressure on the lefthand side of the diaphragm, as viewed in Figure 8. The tension of the diaphragm springs is so regulated that, with the hydrostatic pressure from the balance pipe, the valve 13 will remain closed when there is less than a predetermined relatively small quantity of liquefied refrigerant on the right hand side of the diaphragm so as to insure a seal at all times between the expansion pipe 30 and the condenser. When, however, condensed refrigerant collects in the trap and passes down the pipe 10 so as to fill the latter above the said predetermined level, the weight of the refrigerant then becomes sufiicient to overbalance the spring controlled diaphragm, thus opening the valve 13 and permitting passage of the refrigerant to the expansion pipe 30. In this connection, it will be observed that both sides of the diaphragm are subject to the same vapor pressure existing in the trap and hence, the diaphragm is subjected to little stress and the only pressure difierence acting on either side thereof is determined by the height of tne liquid columns in the pipes 68 and 10. Preferably, actuation of the diaphragm and opening of the valve will be set to occur when the refrigerant collecting in the pipe 10 about half fills the same.

From the expansion valve B, the refrigerant passes through the expansion pipe 30 to the flash drum 3|. The latter, shown conventionally as between the two coils D and E in the diagrammatic view of Figure 1, is preferably, in actual practice, located near one side of the car at the U ends of the coils, as best shown in Figures 2 and 4. The vapor released in the flash drum, immediately passes vertically upward through the separator dome I35 from the top of which it passes off into the main suction line 29, as hereinbefore described. In actual practice, the level of the refrigerant in the drum 3| will be kept approximately midway thereof, as indicated in Figure l, the drum being so located that the level of the refrigerant therein will normally be slightly above the admission ends of the first of the series of expander tubes of both coils D and E, hereinafter described in detail.

From the flash drum 3!, the refrigerant is fed from the bottom thereof through passage 11 to the central valve chamber 18 of the distributor valve C, best shown in Figures 9 and 10. In the main block of the distributor valve, are disposed two ported nuts 19 and 80 having valve seats 8| and 82, respectively. Cooperable with the seats 8| and 82 is a double valve 83. The valve and valve seat 8| control an outlet port 84 and the valve and valve seat 82 control another outlet port 85, as clear from Figure 9. The port 84 is in communication with the delivery pipe I leading to the first expander tube of the cooling coil D and the port 85 is in communication with the pipe I85 leading to the first expander tube of the accumulator coil E. The valve 83 has oppositely extended stems which are connected with diaphragms 86 and 87 mounted within the distributor valve. Each of the diaphragms is subjected to spring coils 88 and 89 on its outer side,

respectively, as shown in Figure 9. The tensionof the spring 89 is adapted to be adjusted for different temperature ranges through the lever 96 associated with the indicator dial 9I, all as more specifically described and claimed in my prior pending application 645,697, filed December 5, 1932, for improvement in Temperature controlled vehicles and to which reference may be had for a full and complete disclosure. The chamber on the outer side of the diaphragm 85 is in communication with the pipe 92, which in turn leads to a thermostatic bulb 93, preferably located in the top center of the pay-load compartment II of the car. As the temperature in the latter varies, so will the vapor pressure on the outer side of the diaphragm 86 vary, thus effecting control and movements of the double valve 83 and regulating the distribution of the refrigerant to the ports 86 and 85, all as fully set forth in my said application 645.697. In Figure 9, the valve 83 is shown in middle or neutral position, under which condition the refrigerant is distributed simultaneously to both ports 84 and 85 and hence to both coils D and E. When the temperature in the payload compartment drops down to or below the upper limit of the predetermined range of payload compartment temperature, the valve 83 seats on the valve seat 8|, thus closing off refrigerant supply to the main cooling coil D and allowing full supply to the cold accumulator. Conversely, when the temperature of the pay-load compartment rises above the upper limit of the predetermined temperature range, the vapor pressure on the outer side of the diaphragm 86 is increased so as to move the valve 83 onto the seat 82, thus shutting off refrigerant supply to the cold accumulator and allowing of full supply to the cooling coil D. Between the two extremes referred to, the valve 83 will automatically adjust itself to varying intermediate conditions as required. Another port 95 is formed in the valve casing communicating with the valve chamber I8 and extending downwardly, said port 95 having disposed therein a gravity check valve 96. The port 95 communicates with branch pipe 285, which in turn is in communication with the pipes I85 and 37 leading to the cold accumulators. The function and operation of the port95, check valve 96 is explained hereinafter.

Assuming that the temperature of the pay-load compartment is such as to require the maximum refrigerant in the main cooling coil D, the port 85 is shut off and the port 84 open, as hereinbefore explained. The refrigerant, therefore, feeds through the pipe I 84 (and branch line 36 to the opposite end of the car) to the coil D. In the diagrammatic and simplified view of Figure 1, the cooling coil D is illustrated with only three headers arranged in the order of I-2-3. In actual practice, however, a more practical and efficient arrangement is as illustrated best in Figures 2, 3, 4 and 6, which is now considered the preferred arrangement. In the preferred arrangement, five headers are employed as shown arranged in the order of I l-3- 25 and in accordance with which the headers are referenced Mil, AIM, 603, 402 and 465. Each of said headers is in the form of a relatively large tube sealed at its ends and extending approximately the full height of the refrigerating compartment. At the bottoms, all of said headers are in communication with each other by connecting pipes 9I9'I terminating in a draw-off branch 98 controlled by globe valve 99. By this means, oil collecting in the headers may be drawn off from time to time as desired. At their tops, the headers are also in communication with each other by means of connecting pipes I -I B0 and the first, or header MI, in communication with the suction pipe 35 as previously described. Hence, it will be seen that each header is in free communication with the separator dome I35 and, also, with the main suction line 29.

Referring more particularly to Figures 2 and 6, each flooded recirculating expander tube (50-51 etc.) comprises a vertical drop leg disposed within a header, as indicated at I50 for the first tube of the series and I! for the second tube of the series, and so on, and a riser outside leg as indicated at 250 for the first tube, I for the second tube of the series and so on. The first tube of the series 58, I50, 250 has its drop leg within the first header (WI and is then extended to the exterior of the header at the bottom, as shown in Figure 2, the tube then being bent around to the rear and passing the rear of all of the headers and thence brought in front of all of the headers and thence in back of headers GUI, (464, 103 where it terminates in a delivery end 359 within the header 402, the riser leg being in generally helical form and with the delivery end 350 above the admission end 550 of the drop leg within the header lIlI. Where the feed pipe I84 enters the header 40L the same is vented as indicated at 286 so as to allow such vapors as have formed in the pipe I84 to be separated from the remaining liquefied refrigerant and pass immediately into the header and upwardly to the top thereof and thence direct to the suction line. Similarly, at the delivery end 350 of the tube, a vent 550 is provided for the separation and escape of the vapors formed in the riser leg from the remaining unvaporized or still liquefied refrigerant, the vapor passing off immediately into the header 602, rising to the top thereof and then passing through the connector pipes I08 and so on to the suction line 29. The remaining liquefied refrigerant from the first tubeis delivered from the end 350 thereof to the admission end Ii5I of the drop leg of the second tube, the liquid then dropping in the latter and starting to circulate in the second tube. The second tube passes around in back of the header 305, then in front of all the headers, thence in back of all of the headers, then in front of headers 6B5, 402 and is finally entered into header 403, where the vapor is separated from the remaining liquefied refrigerant and the latter passed onto the third tube 52 of the series and so on. Preferably, as shown, the ratio of the heights of the drop leg to the riser, expander or evaporator leg of each tube will be as five to six and, as shown, I9 such stepped or multi-lift tubes employed in the coil. In this connection, it will be noted that each drop leg is exposed on all sides to the cold vapors and/or liquid in the header and thus greatly shielded from the influx of heat from the outside, whereas each riser, evaporator or expander leg, which is of much greater.- total length than the drop leg, is fully exposed to the outside heat and hence there will be promoted relatively rapid evaporation or expansion and rise in the riser leg to permit the successive step by step separation of vapor from liquefied refrigerant as the process is continued. Preferably, the tube and header connections are as shown in Figure 7 where a four way casting I02 is employed into which the respective ends'of the tubes or pipes are entered, those pipes passing through the header being preferably welded thereto, as indicated at I03. Also, to permit of separation of any oil that may be present in the refrigerant, at the bottom of each drop leg, the four way cast ing will be provided with a small drain hole, as indicated at I04, thus permitting the oil to drop to the bottom of the header from which it may be drained off, as hereinbefore described.

The coil arrangement shown and described is compact while at the same time providing a large amount of exposed surfaces for the expander tubes. The coil arrangement is located immediately behind the bulkhead I4 and suitably secured to a plurality of vertically extending channels I05 bearing against the inner face of the bulkhead. Referring to Figure 4, it will be noted that the channels are arranged in pairs with the open sides facing each other, thus providing fines or pamages I06 through which the air, as chilled, will circulate relatively rapidly in contact with the adjacent tubes. In addition, the air is, of course, free to circulate between each pair of channels as well as down through and around the other parts of the cooling coil.

The last or uppermost of the series of expander tubes 53 has its delivery end extended into the header 405 where it is vented, as indicated at 353, to allow the vapors to pass off into the header but differs from the remaining tubes in that it is so continued through the header 405 as to' deliver any liquefied refrigerant into the pipe 201, which is extended outwardly of the bulkhead and thence downwardly where it communicates with the lower header I01 of the ceiling or auxiliary cooling coil F. The latter is provided also with an upper header I08, the two headers extending transversely of the car and suitably supported from the ceiling by brackets I09, links III] and bottom brackets III. At the end opposite to that supplied by the pipe 201, the two headers I01 and I08 communicate with a ceiling coil accumulator II2, as best shown in Figure 5. In communication with the headers I01 and I08 are a plurality of expander tubes, each having a lower and generally upwardly inclined leg II3 looped at its outer end and with an upper horizontal leg IH. Said ceiling expander tubes are preferably arranged in pairs, as best shown in Figure 5, and the same may be supported at their outer ends from the ceiling of the car by brackets I I5, shown in Figure 3a. Beneath each pair of ceiling tubes is a suitable drip pan II6 sloped at its inner end and leading to a main horizontal drip pan II 1, the latter being so positioned as to permit any condensates thereon to drip over into the refrigerating compartment behind the bulkhead and from the bottom of which the same may be drained to the exterior of the car in the usual manner. From the top of the accumulator II2 extends a pipe 2I2 either constituting a part or an extension of the suction pipe 35 hereinbefore referred to and by means of which the vapors are adapted to be conducted to the main suction line 29.

With the ceiling coil arrangement shown, should there be any liquid refrigerant delivered from the last expander tube of the main coil, the same will automatically be passed to the ceiling coil and there circulated and evaporated, the vapors, as formed, being conducted to the main. suction line and liquefied refrigerant being adapted to recirculate until completely vaporized.

The coil of the cold accumulator is preferably made the same, as that of the main cooling coil D and need not be separately described. In the case of the cold accumulator, the coil has the major portion thereof, in the preferred construction as best shown in Figure 3, disposed within the brine tank 32. The latter is provided with heavy insulation on all sides as indicated at II8, the front wall of insulation between the cold accumulator and main coil D being extended practically up to the ceiling and circulation of air over the cold accumulator being shut off by a metal shield I I9, as shown in Figure 3. Access may be had to the cold accumulator through the usual refrigerator car hatch indicated at I20. The tank 32 will be filled with any suitable congealable liquid solution, such as sodium chloride, calcium chloride or magnesium chloride, such liquid solution, for convenience, being hereinafter termed brine. As will be understood, no auxiliary ceiling coil is employed with the cold accumulator coil but otherwise its construction and operation will be preferably identical with the main coil D, as described. Passage of the vapors from the cold accumulator coil to the main suction line is by means of the pipe 34 previously referred to. The operation of the apparatus, when all of the refrigerating capacity is required for the payload compartment has previously been set forth. When the opposite extreme condition obtains, that is, when no refrigerating capacity is required for the pay-load compartment, the position of the distributor valve will be reversed. In such condition, the valve 83 will be on the seat 8 I, thus shutting off the port 84 and providing free communication with the port 85 and hence to the accumulator soil; at both ends of the car. So long as this condition continues, cold is stored in the accumulators, thus cooling the brine and ultimately congealing it, the liberated vapors passing to the suction line 29 and back to the compressor, thus continuing the process. Various intermediate conditions will obviously occur where part of the delivered refrigerating capacity from the compressor will be delivered to both the main cooling and accumulator coils.

Still another condition may obtain as when the car is stationary or the compressor is delivering insufficient refrigerating capacity to bring down the temperature of the pay-load compartment to the desired point, thereby rendering it necessary to draw upon the cold stored in the cold accumulators. Under this last named condition, a circuit for the refrigerant is set up between each set of coils D and E, wherein the latter function as condensers for the refrigerant vapors coming over from the top of the coil D through the pipes 3335--34 to the tops of the headers of the accumulator coil E. As said vapors enter the headers and tubes of the accumulator coil E, the same will be gradually condensed because of the surrounding chilled or frozen brine, the refrigerant as condensed either dropping directly to the bottoms of the headers or through the drainage holes I 04 at the bottoms of the respective expander tubes, hereinbefore referred to. The result is that a level of the liquefied refrigerant is built up within the cold accumulator above the admission end of the first tube of the series thereof, so that the refrigerant will then feed by gravity through the pipe I85,

thence into the branch pipe 285 to open the check valve 96 and then pass through the port 95 into the valve chamber 18 whence it is free to pass to the port 84 and thence to the cooling coil D, it being obvious that under these conditions, the distributor valve will be so set as to close off the port 85. Where there is no refrigerating capacity at all being delivered from the compressor under the conditions stated, there will obviously thus be formed a completely closed circuit between each set of coils D and E. Where there is only a partial or insuiflcient refrigerating capacity supplied by the compressor. the same circuit exists and augments such refrigerating capacity as is delivered by the compressor, thus insuring the maximum heat transference from the pay-load compartment to the cold accumulators and rapid cooling of the pay-load compartment. When the temperature of the pay-load compartment drops to the lower permissible limit, a balanced condition will be obtained and either the condensation of the refrigerant in the cold accumulators stopped or carried on only to such extent as may be necessary to maintain the pay-load compartment at the desired temperature. By insulating the cold accumulators, all or substantially all of any cold accumulated therein is made directly available for condensing purposes when this is required, thus eflecting the most efiicient transference of the heat units.

From the preceding description, it will be seen that many advantages are inherent in the apparatus disclosed, particularly in connection with refrigerator cars or other vehicles which are subject to such a wide variation of difierences not only with respect to atmospheric temperatures but in the operation of the compressor from zero to maximum capacity. If, for instance, the supply of liquefied refrigerant as fed to the first or lowest tube of the coil is throttled down, the result will be a progressive running dry of the expander tubes from the top successively downwardly until a proper balance is effected. Recirculation in such uppermost dry tubes ceases and the lower tubes are still active and will adjust the liquid levels therein automatically in such manner that the lowermost tubes will feed the liquefied refrigerant to the next succeeding higher tubes until that tube is reached where no refrigerant is passed on to the next. Notwithstanding that certain of the expander or evaporator tubes may be dry as described, the vapors given off will not be superheated since the released saturated vapors, as successively released from each tube are not compelled to pass through any dry tubes but pass directly in a short route to the main suction line. Such upper tubes as are dry or inactive may be said to provide stagnant vapor pockets that have practically no effect on the quality of the total vapor delivered to the suction line.

On the contrary, should there be an excessive supply of the liquefied refrigerant so as to result in a level in the expander tubes above that predetermined as the most advantageous, nevertheless the multi-lift 'or step by step arrangement will function efficiently. Under these conditions, only the lowest tube or tubes will be flooded but the upper tubes will function properly as will be obvious. Furthermore, there is no danger of any of the liquefied refrigerant, even under these conditions, being carried over into the suction line and to the compressor with consequent impaired efliciency. In the present construction, should liquefied refrigerant by any chance succeed in reaching the suction pipe 35, it will be dropped down into the flash drum for recirculation and cannot enter the main suction line 29. It will also be observed that the pressure in all the steps or stages of the coils is the same since all tubes are in unrestricted communication with the headers and hence with the suction line, thus insuring uniformity of the quality of the vapor drawn oil? to the compressor.

In addition to the conditions specifically referred to in the immediately preceding paragraphs, various other conditions will arise where one of the coils if fully open to the infiow of the liquid refrigerant while the other coil is throttled down. In any condition, however, at least one of the coils is always working with its full capacity. For instance, when the distributor valve is in central position and the accumulator tank warm, and the accumulator coil takes too much of the refrigerant furnished by the I compressor while the cooling coil D gets warm, then the supply to the accumulator coil will automatically be throttled down, the total effective heat transfer area of both coils is reduced, evaporation pressure and temperature both drop and the temperature differential, causing the flow of heat, is increased. This takes place with reduced heat transmission area for the accumulator coil while the heat transmission area for the cooling coil remains constant. On the contrary, if the accumulator is cold and the accumulator coil condenses the refrigerant, while the refrigerant supply without the aid of the condensing action is too much for the cooling coil D, the latter will be throttled down to a point where the evaporating temperature has dropped low enough to cause evaporation in the accumulator coil. The cooling coil D, however, will be throttled down so far that even with the increased temperature differential only the desired amount of refrigerant is furnished to the cooling coil D for cooling the payload compartment. The action of the entire system is, therefore, such that the payload temperature is held within the desired limits with the maximum amount of coil surfaces active, thus insuring maximum compressor capacity and thermo co-efiicience of performance.

Although the preferred embodiment of the invention has herein been shown and described, nevertheless various changes and modifications may be made without departing from the spirit of the invention. All such changes and modifications are contemplated that come within the scope of the claims appended hereto.

What is claimed is:

l. A refrigerating apparatus including: a plurality of separately functioning refrigerant expanders of the flooded recirculating type, each expander having its delivery end higher than its admission end; means for feeding liquefied refrigerant to the expanders; means, at the delivery end of each expander, for segregating the vapor formed therein from the remaining liquefied refrigerant; and means for selectively conducting said remaining liquefied refrigerant from the delivery end of each expander to the admission end of another higher positioned expander.

2. A refrigerating apparatus including: a plurality of refrigerant expanders arranged in an ascending series; means for feeding liquefied refrigerant to the admission end of the first and lowest of the series and successively therefrom directly to the next higher of the series and so on; and means for separating the refrigerant vapor from the liquid refrigerant as the vapor is successively formed in and delivered from the delivery end of each expander.

3. A refrigerating apparatus including: a plurality of refrigerant expanders arranged in series, each expander having an admission and delivery end,the admission end of each expander, other than the first, being higher than that of the next preceding expander of the series; means for supplying liquefied refrigerant to the admission end of the first of the series and from the delivery end thereof directly to the admission end of the second and relatively higher of the series and so on; and means for separating and thereafter maintaining separated the refrigerant vapor from liquefied refrigerant between each consecutive pair of expanders.

4. An expander for a refrigerating apparatus including: a plurality of headers; means providing communication between all of said headers and a suction line; a series of flooded type expander tubes each including a drop leg within a header and an outside riser leg, the delivery end of each riser leg terminating within a header and there in communication with the admission end of the drop leg of the next expander tube and vented to deliver vapor to the interior of the header.

5. An expander for a refrigerating apparatus including: a plurality of headers; means providing communication from all of said headers to a suction line; a series of flooded type expander tubes each including a drop leg and a riser leg, the admission end of each tube other than the first, being disposed higher than the admission end of the next preceding tube of the series and similarly with respect to the delivery ends of the riser legs; and means at the delivery end of each riser leg for separating vapor from liquefied refrigerant and passing the vapor to a header and the remaining liquefied refrigerant to the admission end of the drop leg of the next expander tube of the series.

6. A refrigerating apparatus comprising, in combination: a compressor; a condenser; an expansion valve; a flash drum, all connected in series in the order named; an expander coil; connections from the drum to the expander coil;

- a suction line to the compressor; and a dome providing communication from the drum to the suction line, said expander coil comprising a plurality of vertical headers, each in communication with the suction line, a plurality of expander tubes, and vapor and liquefied refrigerant separating means at the delivery end of each tube.

7. In a refrigerating apparatus for vehicles, a main refrigerant expander coil and a supplemental expander coil, said main coil comprising a plurality of independently functioning expander tubes of the flooded recirculating type arranged in a vertical series, each with its admission end at a higher level than the next preceding tube and its delivery end higher than the delivery end of the next preceding tube, means at the delivery end of each tube except the topmost tube, for separating the formed vapors from the liquid refrigerant and passing the latter to the admission end of the next succeeding tube of the series, the supplemental coil being disposed at the top of the main coil and of the flooded recirculating type; and means at the delivery end of the uppermost main coil tube for there separating formed vapors and passing any remaining liquid refrigerant to said supplemental coil.

8. In a refrigerating apparatus, the combination with means for liquefying a refrigerant and delivery and return suction pipes in communication therewith; of an air cooling coil; a cold accumulator, said accumulator and cooling coil being arranged in parallel between and in communication with said delivery and suction return pipes; thermostatically governed refrigerant distributing means for the accumulator and cooling coil; said accumulator including a brine tank and a refrigerating coil, the refrigerating and cooling coils each comprising a plurality of refrigerant expanders of the flooded recirculating type; means at the delivery end of each of the expanders, for separating the vapor as formed in and delivered from each expander, from the liquefied refrigerant.

9. In a refrigerating apparatus, the combination with means for liquefying a refrigerant and delivery and return suction pipes in communication therewith; of an air cooling coil; 2. cold accumulator, said accumulator and cooling coil being arranged in parallel between and in communication with said delivery and suction return pipes; thermostatically governed refrigerant distributing means for the accumulator and cooling coil, said accumulator including a brine tank and a refrigerating coil. the refrigerating and cooling coils each comprising a plurality of refrigerant expanders arranged in series, means for successively feeding liquefied refrigerant from one expander to the next of the seriss, and means for separating the va or as successively formed in and delivered from the delivery end of each expander from the unvaporized refrigerant.

10. In a refrigerating apparatus, the combination with means for liquefying a refrigerant and delivery and return suction pipes in communication therewith; of an air cooling coil; 2. cold accumulator, said accumulator and cooling coil being arranged in parallel between and in communication with said delivery and suction return pipes; thermostatically governed refrigerant distributing means for the accumulator and cooling coil, said accumulator including a brine tank and a refrigerating coil, said refrigerating and cooling coils each including: a plurality of headers, means connecting all of the headers to said suction return line, a series of flooded type expander tubes each including a drop leg within a header and an outside riser leg, the delivery end of each riser leg terminating within a header and there in communication with the admission end of the drop leg of another expander tube and vented to deliver vapor to the interior of the header.

11. In a refrigerating apparatus for vehicles and the like, the combination with a compressor and condenser; of a flash drum; an expansion valve intermediate the condenser and flash drum; a main cooling coil; a cold accumulator including a brine tank and a refrigerating coil therein; a thermostatically controlled distributor valve intermediate the flash drum and the supply ports of each of said coils; a return suction line to the compressor, the same being in communication with the flash drum and with each of said coils, each of said coils comprising a plurality of headers each in communication with the suction pipe, 9. series of expander tubes of the flooded recirculating type, and means for separating the vapor from liquid refrigerant at the outlet end of each tube and passing the vapor to a header and the remaining liquid refrigerant to another expander tube.

12. An expander for a refrigerating apparatus including: a suction vapor header; a series of flooded type expander tubes each including a drop leg and a riser leg, the delivery end of each riser leg being vented to provide vapor communication with said header, the delivery end of each riser leg being in direct communication with the admission end of the drop leg of the next expander tube of the series to deliver remaining liquid refrigerant to the latter.

13. In a refrigerating apparatus, the combination with means for liquefying a refrigerant and delivery and return suction pipes in communication therewith; of an air cooling coil; a cold accumulator including a brine tank and a refrigerating coil, said refrigerating and cooling coils being arranged in parallel between and in communication with said delivery and suction return pipes; thermostatically governed refrigerant distributing means for the refrigerating and cooling coils, said cooling coil comprising a plurality of refrigerant expanders of the flooded re-circulating type; and means at the delivery end of each of the expanders for separating the vapor as formed in and delivered from each expander, from the remain ing liquefied refrigerant.

14. An expander for a refrigerating apparatus including: a vertically extending vapor header adapted to have the top end thereof placed in communication with a vapor suction line; an

ascending series of flooded type expander tubes each including a drop leg and a riser leg, the delivery end of each riser leg, except the last, being connected to the admission end of. the drop leg of the next tube of the series to convey liquid refrigerant directly thereto; and means at the delivery end of each riser leg for delivering vapor formed therein directly to the interior of the header for direct passage of the vapor from the entire series of tubes through the header to the suction line, all expander tubes thereby being maintained under the same pressure.

15. In a refrigerating apparatus, the combination with means for liquefying a refrigerant and delivery and return suction pipes in communication therewith; of a cooling coilv exposed to air circulation; a cold accumulator including a brine tank and a refrigerating coil, said refrigerating and cooling coils being arranged in parallel between and in communication with said delivery ,and suction return pipes; thermostatically governed means for distributing the refrigerant, in accordance with load requirements, to the refrigerating and cooling coils, said refrigerating coil comprising a plurality of refrigerant expanders of the flooded recirculating type; and means at the delivery end of each of said expanders for separating the vapor as formed in and delivered from each expander, from the remaining liquefied refrigerant.

16. In a refrigerating apparatus for vehicles and the like, the combination with a compressor and condenser; of a flash drum; an expansion valve intermediate the condenser and flash drum; a main air cooling coil; an insulated accumulator including a brine tank and a refrigerating coil; thermostatically controlled distributor means intermediate the flash drum and the supply ports of each of said coils; a return suction line to the compressor; means providing communication between the delivery ends of each of said coils and the return suction line whereby said coils may be operated in parallel; means providing communication between the fiash drum and the return suction line; and means providing communication between the delivery ends of the two coils whereby the latter may operate in series in a closed circuit with the insulated accumulator functioning as a condenser.

CARL W. SPOHR. 

